Free tool
Shock index calculator.
Catches occult shock the pressure alone will miss. HR ÷ SBP, interpreted.
Shock index
0.75
Mild elevation
Early compensated shock possible. Reassess trend.
Adult thresholds
- 0.5–0.7 — normal
- > 0.9 — significant hypoperfusion likely
- > 1.0 — massive transfusion predictor in trauma
Pediatric (SIPA)
- 4–6 yr: abnormal > 1.2
- 7–12 yr: abnormal > 1.0
- 13–16 yr: abnormal > 0.9
Frequently asked
- What is shock index?
- Shock index = heart rate ÷ systolic BP. It flags occult shock earlier than SBP alone by catching compensated patients whose HR is rising before their pressure drops.
- What shock index is abnormal?
- Normal is 0.5–0.7. > 0.9 suggests significant hypoperfusion; > 1.0 predicts massive transfusion need in trauma and worse outcomes in sepsis.
- What is the modified shock index?
- MSI = HR ÷ MAP. It weights diastolic pressure. > 1.3 is associated with increased mortality.
- Is there a pediatric shock index?
- Yes — SIPA (shock index pediatric age-adjusted). Thresholds: 4–6 yr > 1.2, 7–12 yr > 1.0, 13–16 yr > 0.9.
For educational and exam-preparation use only. Not medical advice.